Mostly when I blog about diverse science and fiction and fantasy for kids, the books are about characters who don't happen to be white, because other diversities (LGBT protagonists, and kids with disabilities that aren't magically cured being somewhat thin on the ground in speculative fiction books for kids and younger teens). So just for kicks, here are my favorite spec fic books that including those diversities.
The Door Into Fire, by Diane Duane, and I pretty much read this fantasy epic to pieces. Herewiss is a magic user, his loved, Freelorn, is the exiled heir to a kingdom, and there is just tons of great fantasy world build and sexy times of all sorts. I myself thought Freelorn was kind of wet (I think I just took against the name right from the beginning), and I was rooting for Herewiss' relationship with a really wonderful fire elemental being (who sometimes took male form, sometimes female, for the sexy good times)....because really a self-confident but poignantly vulnerable shape shifting elemental love interest is more interesting. The other two books in the series that were published (Door into Shadow, and The Door Into Sunset, are fine too, but not quite as preconception-of-sexuality shifting as this one was!
Thendara House, in which two women from different patriarchal societies (one is from Earth and one from Darkover) come to love each other, was a particular favorite, and can be read a stand-alone just fine. I think I liked this one because I've always enjoyed reading about close communities of women--there's often a comfortable safeness to this sort of book, that in no way precludes emotional and external tensions and adventures, and I also love to read about struggles to navigate social norms in alien cultures.
Demon's Lexicon series because I love him and he is wonderful and he is kind and smart and loves books and I love him. And the books in which he appears are pretty darn good too.
My second favorite spec fic protagonist with a disability is Eugenides from Megan Whalen Turner's Queen's Thief series, who has only one hand. He is awesome, and the books are awesome (especially The King of Attolia). I am putting him after Alan because he is so awesome I can't even imagine crushing on him from afar in real life (perhaps in part because the relationship that he's actually in is so perfectly tight that there's no room for strangers to crush on him much).
For cultural and ethnic diversity reimagined in speculative fiction, Ursula le Guin is my go-to author. Always Coming Home, is an novella set in the future that's situated within an anthropological framework based on Le Guin's extensive knowledge of Native North America. It's taken me some years to realize how much I appreciate it, but after reliving it countless times while weeding the garden (a benchmark by which I measure books is how clearly and how often my mind offers them back to me again while weeding), I've realized that I truly love it.
Four Ways to Forgiveness, four stories set on a planet and its moons where dark skinned people enslaved pale skinned people. In order for this world to become part of the galactic community, the inequities of this culture must be resolved, and it's a difficult and painful process. The characters in these stories are some of Le Guin's most memorable, which is saying a lot. And I'm also fond of this one for personal reasons--when I first met my husband, it had just come out, and both of us had it on our respective nightstands.